A280133 Partial products of A057661 (Sum_{d|n} psi(d)).

1, 2, 8, 48, 528, 5808, 127776, 2811072, 87143232, 2788583424, 156160671744, 6090266198016, 481131029643264, 31273516926812160, 2314240252584099840, 199024661722232586240, 27266378655945864314880, 2508506836347019516968960, 431463175851687356918661120

Offset: 1

Author

Jaroslav Krizek, Dec 27 2016

Keywords

• nonn

Comments

psi(n) is the sum of the totatives of n (A023896).

Crossrefs

Cf. A000010, A057661, A232533 (partial sums of A057661), A280132 (partial products of A029940).

Programs

Magma

[&*[&+[&+[h: h in [1..d] | GCD(h,d) eq 1]: d in Divisors(k)]: k in [1..n]]: n in [1..1000]]

Mathematica

FoldList[Times[#1, #2] &, Array[Sum[Total@ Select[Range@ d, CoprimeQ[#, d] &], {d, Divisors@ #}] &, 19]] (* Michael De Vlieger, Dec 27 2016 *)

Formula

a(n) = Product_{i=1..n} A057661(i).